Lesson 2 - Page 1



Stamp honoring Nasir
al-Din al Tusi

Joseph Black

Henry Cavendish

Mikhail Lomonosov

One of John Dalton’s Rules states that “matter cannot be destroyed.”  This rule was based on the work of on several people prior to Dalton.    As early as the 13th century Nasir al-Din al Tusi (1201-1274), an astronomer and mathematician from Persia (present-day Iran), wrote that matter can change, but it does not disappear. 

During a chemical reaction there is no detectable increase or decrease in the quantity of matter.  In chemical reactions you must take into consideration the changing of compounds into other compounds.  Conservation of Mass was difficult to confirm until experimentation on the interaction of atmospheric gases were understood.    There were chemists working on gas theories including Jean Rey (1583-1645),  Joseph Black (1728-1799), and Henry Cavendish (1731-1810).  However they never could collect enough data because it was difficult to trap gases.  It was not until the invention of the vacuum pumps in 1671 by Robert Hooke, could the weight of gases be used to confirm the Conservation of Mass.

Mikhail Lomonosov (1711 – 1765) and  Antoine-Laurent de Lavoisier (1743-1794) had previously written about similar ideas.  They did several experiments that seemed to prove this notion.    The Law of Conservation of Mass/Matter (also known as the Lomonosov-Lavoisier Law) states that mass in a closed system will remain the same.  Hence, matter cannot be created nor destroyed but can be rearranged.   This began the understanding of chemical reactions and the identification of the resulting products.  In an ordinary chemical reaction, there is no increase or decrease of the quantity of matter.  This was one of the fundamental rules proposed by John Dalton.   


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